Acute manic episodes linked with high rates of bacterial infection

Patients with bipolar disorder experience two distinct types of abnormal psychological states: mania and depression. Most people are familiar with depression, as its sub-clinical form is common to the human condition. Mania refers to an abnormal mood featuring racing thoughts, impulsivity, hyperactivity and delusions. While manic episodes are a defining trait of bipolar disorder, they can also manifest as an acute condition in people without a bipolar diagnosis.

Previous findings have linked cases of acute mania with increased immune system activity, but have not clarified the source of the reaction. New research published in the journal Bipolar Disorders identifies excessive rates of bacterial infection as a potential basis for the immuno-activation that has been associated with acute manic episodes.

A team of researchers led by Robert Yolken performed the experiment by evaluating antibiotic prescription rates for sufferers of acute mania. The study included three types of subjects: patients hospitalized for acute mania (n = 234), patients hospitalized for another psychiatric condition (n = 368) and a control group from the non-psychiatric general population (n = 555). Conditions requiring antimicrobial medications were identified from health records, supplying the information needed to calculate the prescription rates related to bacterial infection.

Logistic regression modeling generated odds ratios showing that acute mania was associated with a significantly higher likelihood of being prescribed antibiotics for a bacterial infection, when compared to the other testing groups (psychiatric and control). There was no significant difference in antibiotic rates between any other subgroup and the control. A gender difference was observable for physical site of the related infection. Females were mostly prescribed antibiotics for urinary tract infections, while males more often suffered from infections related to mucous membranes and the respiratory tract.

Acute episodes of mania within the otherwise non-psychiatric population appear to be linked with an increased presence of bacterial infections. These findings could be a result of several underlying processes. Acute mania may be instigated by bacterial infections, or it is possible that both conditions are facilitated by an unidentified third source.

Additionally, the use of antimicrobial prescription rate as a correlate of actual bacterial infection makes it possible that the relationship is actually between acute mania and the antibiotics themselves, or even a result of the inclination of physicians to prescribe them. Future studies would benefit from confirming diagnoses with blood samples or other direct measures and by controlling for differences in the overall rate of antibiotic usage by individual physicians.